Abstract

PURPOSE: Aim of the study is to assess the contribution of peri-articular soft tissues to hip joint kinematics and their influence on hip stability. METHODS: Four hemi-corpse specimens (3 males, average age 72 years) were studied using a custom navigation system. Hip kinematics (femoral head motion relative to the acetabulum and joint range of motion) were evaluated with the hip manually positioned in 36 different positions with (I) soft tissues intact, (II) after removal of the skin and muscles and (III) after partial capsulectomy. Each position was repeated 3 times in each state. RESULTS: Excellent interclass correlation for each test was determined (ICC range, 0.84-0.96). Femoral head anatomical centre displacement relative to the acetabulum occurred in all 3 planes, even with all the soft tissue intact (average, 3.3 ± 2.8 mm lateral translation; 1.4 ± 1.8 mm posterior translation and 0.3 ± 1.5 mm distally). These translations increased as more soft tissue was removed, except medial-lateral displacement, with an average 4.6 ± 2.9 mm lateral translation, 0.7 ± 1.3 mm posterior translation and 1.5 ± 1.9 mm distal translation when partial capsulectomy was performed. Range of motion increased in all 3 planes with increasing removal of the soft tissues. CONCLUSIONS: This study showed that femoral head anatomical centre displacement within the acetabulum occurs and increases with increasing removal of peri-articular soft tissues, confirming their influence on hip stability. Hip kinematics was also influenced by peri-articular soft tissues; specifically range of motion increases with increasing removal of those tissues. From clinicians' point of view, they have therefore to consider the influence of their surgeries on peri-articular soft tissues, since excessive translations may promote hip arthritis.

Abstract

Inflammation and subsequent fibrosis, adhesions, or plicae may limit normal capsular compliance and decrease volume capacity of the knee.Patients with fibrosis, anterior interval scarring, adhesions, or palpable painful plicae will have decreased knee volumes when compared to controls, and selective arthroscopic releases will restore volume to normal levels.Descriptive laboratory study and cohort study; Level of evidence, 2.In part I, knee volume and pressure were recorded in 14 fresh-frozen human cadaveric knees, and the maximum volume capacity was identified before capsular disruption. In part II, 49 patients undergoing arthroscopy were divided into 2 groups based on intraoperative volume assessment at 50 mm H(2)O pressure: group 1 (n = 20) with normal volume (<1 standard deviation below the mean established in part I) and group 2 (n = 29) knees with deficient volume (>1 standard deviation below mean). Group 2 underwent volume-changing procedures such as lysis of adhesions, anterior interval release, and plica resections, while group 1 underwent volume-neutral procedures including meniscal or chondral surgery. The knee volume was then reassessed after arthroscopy.The average volume capacity of the knees in the cadaveric study was 87.5 ± 21.7 mL (range, 50-120 mL). There was no statistical difference between the presurgical (98.9 ± 29.8 mL) and postsurgical volumes (99.4 ± 29.1 mL) in group 1; P = .65. The presurgical volume in group 2 (46.1 ± 13.0 mL) was significantly lower than group 1 (P = .001). The group 2 volume increased to 78.5 ± 24.2 mL after surgery (P = .001), with an average change in volume of 75.5%. The mean change in volume after surgery was significantly greater in group 2 (32.3 mL) versus group 1 (0.45 mL) (P = .001). At 1-year follow-up, the mean Tegner score in the volume-compromised group 2 increased from 2.0 ± 1.4 preoperatively to 4.0 ± 2.0 postoperatively (P = .01), the Lysholm score increased from 45.0 ± 24.0 preoperatively to 76.8 ± 25.4 postoperatively (P = .003), and the average Short Form-12 quality of life score increased from 32.4 ± 8.7 preoperatively to 45.0 ± 11.0 postoperatively (P = .005).The average volume of the human knee in this study was between 65 and 110 mL (±1 standard deviation of mean of 87.5 mL). Although patients with chronic knee pain may have pain from multiple sources, some may have diminished knee volume, and selected arthroscopic releases can restore knee volume to near-normal levels.

Abstract

Femoroacetabular impingement (FAI) represents an underlying bony abnormality of either the femoral head-neck junction or acetabulum, or most commonly, both. This often is associated with damage to intra-articular structures, primarily the labrum and chondral surfaces. Like pincer impingement, cam impingement has been associated with pain, limited hip range of motion, pain affecting athletic performance, and has been linked to the development of osteoarthritis. Cam impingement is the loss of offset of the femoral head-neck junction associated with loss of sphericity of the femoral head. Isolated cam impingement, although more common than isolated pincer impingement, it is much less common than both cam and pincer coexisting in people with FAI. Classically, the patient with isolated cam impingement is a young athletic male near 20 years of age. The classic pathology associated with the cam lesion is an acetabular articular cartilage injury in the anterosuperior acetabulum that is fairly well defined and may be deep, 1 to 1.5 cm from the acetabular rim, initially sparing the labrum, but eventually leading to labral detachment from the underlying bone. Treatment generally focuses on restoring the femoral head-neck offset by removing the excess bone. This article will review the underlying pathology of cam-type FAI, the evaluation and diagnosis, arthroscopic treatment, and reported outcomes.

Abstract

The purpose of this study was to develop a method of femoral fixation for complex revision anterior cruciate ligament (ACL) reconstructions that would avoid a staged bone grafting approach. We evaluated the use of a calcium phosphate cement as a structural bone void filler that would allow for a single-stage revision ACL reconstruction with initial biomechanical properties equivalent to standard autologous bone-patellar tendon-bone primary ACL reconstruction.We tested 11 matched pairs of fresh-frozen cadaveric knees (N = 22). Controls were treated with autologous bone-patellar tendon-bone primary ACL reconstruction fixed with bioabsorbable interference screws with a 1-mm back wall. The contralateral knee of each pair had a large bone void created that would hamper subsequent femoral fixation to simulate revision ACL reconstruction conditions. This defect was filled with calcium phosphate cement arthroscopically. After solidification, the femoral tunnel was drilled through the bone void filler and native bone with a 1-mm back wall, allowing anatomic positioning. The autologous graft was then placed and fixed with a bioabsorbable interference screw. Specimens were then tested in an MTS machine (MTS Systems, Eden Prairie, MN) for load to failure according to a standard protocol and compared with matched controls.Failure loads for the control group averaged 312 N (standard deviation [SD], 127 N) and were not significantly different compared with the calcium phosphate cement revision group, which averaged 301 N (SD, 95 N) (P = .80). Failure occurred at the femoral bone block in both groups but without screw pullout.Statistical analysis failed to show a significant difference between the control group and the group undergoing structural bone void filler revision in this biomechanical evaluation of initial fixation strength.This technique may allow surgeons to perform a single-stage revision ACL reconstruction in the presence of a contained bone void and avoid the need for a staged procedure if clinical studies verify long-term incorporation of the bone void filler.

Abstract

Revision anterior cruciate ligament (ACL) reconstruction often requires a two-stage approach. This study analyzes the biomechanical properties after cyclic loading of a one-stage ACL revision technique using a calcium phosphate bone cement.Arthroscopic reconstruction of the ACL was performed in 5 matched pairs of fresh-frozen cadaveric knees separated into two groups. The control group underwent a standard reconstruction with a bone-patellar tendon-bone autograft with bioabsorbable interference screw fixation. The experimental group simulated a failed reconstruction by drilling a 12 mm hole and underwent a revision after filling it with a bioabsorbable calcium phosphate bone cement. The specimens were dissected, scanned for bone mineral density, and cyclically loaded on a mechanical testing system (preload of 250 cycles of 5-75 N at 0.5 Hz followed by 10,000 cycles of 20-150 N at 1 Hz). Intact specifmens underwent a load-to-failure protocol of 50mm/min. Ultimate load, stiffness, and modes of failure were recorded. Data was analyzed using paired t-tests.All specimens completed the mechanical testing protocol. The control group had a mean maximum load of 471.33 N (SD 220.73 N) and the experimental group had 453.54 N (SD 152.36; p=0.84). There were no statistically significant differences in maximum load or stiffness. No correlation between bone mineral density (BMD) and maximum load was found.Using calcium phosphate filler in a single-stage ACL revision is biomechanically viable. Further testing of long-term incorporation of the ACL graft in an animal model, along with human clinical trials, should be performed before there is clinical acceptance of this technique.

Abstract

We present a patient in whom an uncemented porous-coated acetabular cup underwent early catastrophic failure due to debonding and was successfully managed with a revision total hip arthroplasty. Early bead shedding of an acetabular cup leading to a sudden component failure requiring revision surgery is a rare event.

The Proliferative and Antiapoptotic Effects of Substance P and Facilitated by Formation of a Beta-Arrestin-Dependent Scaffolding ComplexProceedings of the National Academy of the United States of AmericaDefea KA, Vaughn ZD, O'Bryan EM, Nishijima D, Dery O, Bunnett NW2000; 97 (20): 11086-11091